Here is a web site that can answer most of your questions about high tunnels.

Here is a link that might be useful: high tunnels info

It sounds like you have begun a journey. You have selected two good crops to work with. A few concerns from my experiences: You are starting a little small in structure size. My first is a 20'x96' and I consider it small. A larger structure has more air buffering capacity and the framework is usually heavier so that it can support the weight of the tomato plants if you use stringline support (my recommendation, also means growing indeterminate plants).

I would say if your last FF date is April 30 you could have tomatoes in the tunnels now with a little extra heat on a few nights. My last FF date is May 20 and I hope to be setting plants out next week. This may seem a little early but when does your farmers' market open? The cost of a few nights of propane heat is easy to recover in the first few markets.

Putting plastic film on the structures should be done when the temps are in the 70sF. too cold and you can't stretch the film enough to get a tight fit. Too hot and it will overstretch. You will be able to secure it temporarily next week. Are you using wirelock system to secure? What about ventilation? I assume you are using rollup sides but in the spring and fall I use an exhaust fan. Having electric may seem like deviating from the defined high tunnel but I do what works best for my crop and I advise you to do the same. Unless laws in your state limit you use whatever technology works for you.

I could go on for pages of things that have worked and things that I do without but Just about every major land grant university in the country is doing some high tunnel testing. Penn State has 40+ at their research station. The thing that amazes me most is how little useful material is available.

bmoser

Thanks for the info! I know my structures are going to be small. This is a hobby of mine. I enjoy working outside and taking care of my kids. I am not growing things to get rich, but I do enjoy the extra income at the end of the month. I wish I could go bigger, but cost is my biggest issue. We used too much of my hobby money to finish off half our basement last winter. If I can make these smaller structures work, my wife agreed to let me build them bigger in the fall and next spring.

I am not going to use a wirelock system. I have read about them, but with my size, it doesn't make sense. I am going to try to have small roll up sides. About ventilation, I live in a very windy location, so I know if I open up the south end, the wind will blow! Just as long as it doesn't blow them away!

I am encouraged to hear how soon you put out plants. My market doesn't open until June 21st. By my garden records, If I can put plants out by the end of March or first week in April, I will be in business!

I am going to be building these structures next week. Once I am finished, I will post pictures.

Thanks for the comments!

I agree with BMoser. Go as big as you can afford. Also, do not try to put one up on pure clay soil like I did. The posts were nearly impossible to pound down to the proper level, even with pilot holes, and the end-sills heaved a lot this winter (this is Maine, PLENTY of cold and snow), all because of the poor drainage on my site. I had to site mine so that my wife would approve, it is quite a distance from our house, which makes clearing a path to it thru the snow quite labor intensive, plus running electric and water to it require long lengths of hose and wire. Remember to construct a structure strong enough to withstand high winds and snow/ice load - something strong enough to do that should be plenty strong for stringline support of your plants. Good luck and have fun growing!